1. Technical Field
The present disclosure relates to a vehicle lamp unit which uses a semiconductor light-emitting element as a light source.
2. Related Art
In recent years, a vehicle lamp unit which uses a semiconductor light-emitting element, such as a light-emitting diode, as a light source, has frequently been adopted. Meanwhile, since the light flux of the semiconductor light-emitting element as a light source is small compared to a discharge bulb, a halogen bulb, or the like, for example, it is necessary to secure a sufficient amount of irradiation light through a configuration including a plurality of vehicle lamp units as in a vehicle illumination lamp described in JP-A-2005-294176.
The vehicle illumination lamp described in JP-A-2005-294176 includes a cylindrical lens which extends in the right-and-left directions, a plurality of light emitting elements (semiconductor light emitting elements) which are arranged at predetermined intervals in the right-and-left directions, and a plurality of reflectors which reflect light toward the front from the light emitting elements, and enhances the utilization rate of light flux to secure the amount of irradiation light.
A vehicle headlight described in JP-A-2004-95480 includes a plurality of lamp units which uses semiconductor light-emitting elements as light sources, and is adapted to be able to form a light distribution pattern with a desired pattern shape and light intensity (illuminance) distribution, using at least two types of lamp units among a projector type lamp unit, a direct-radiation-type lamp unit, and a reflective lamp unit.
Generally, in the light emitted from semiconductor light-emitting elements, an illuminance distribution exists such that the illuminance in the vicinity of the center of the light is large, and the illuminance is abruptly reduced as it moves away from the center. Thus, the light projected by a lamp unit including one semiconductor light-emitting element illuminates only a relatively narrow region in the vicinity of the center. Therefore, even in the vehicle lamp units described in JP-A-2005-294176 and JP-A-2004-95480, a region with weak illuminance exists between a plurality of semiconductor light-emitting elements or between respective optical axes of the lamp units, and it is difficult to obtain an irradiation pattern with uniform illuminance. Then, if a plurality of light emitting elements or lamp units is not used, it is difficult to obtain a wide irradiation pattern.